Yoke for locomotive draft gear

ABSTRACT

A yoke for use in a railway locomotive draft gear assembly is provided. The yoke includes a back wall, a front wall and top and bottom straps that extend from the front wall to the back wall. The front wall includes two side sections and a bottom section and a top section. The top strap and bottom strap are tapered to a reduced width along their respective outer edges. The top strap and bottom strap have a reduced lateral extent from their respective intersections with the front wall and the back wall.

BACKGROUND OF THE INVENTION

The present invention relates to railcar coupling systems, and more particularly to a yoke for use in draft gear assemblies used in conjunction with draft sills and couplers in locomotives.

Draft gear assemblies form the connection between the couplers at the ends of adjoining railroad freight cars and the draft sills at the ends of the freight cars. The draft sills are commonly cast or fabricated sills that are mounted at the ends of the center sills of the railcar. The draft sills have a pair of front stops and a pair of rear stops, with a draft gear pocket between the stops. The draft gear assembly is received in the draft gear pocket.

Each draft gear assembly is connected to one coupler, and couplers of adjacent rail cars are connected to form the train. The train may be one hundred cars long and drawn or pushed by one or more locomotives. Typically, there is a limited amount of slack or free movement allowed between the cars. This slack permits the rail cars limited movement toward and away from each other in response to train action and yard impact events.

Train action events include, for example: locomotive start up and acceleration; dynamic braking; differences in braking forces of adjacent cars; and gravity-induced movement of the cars as the train moves onto and away from inclines. Yard impact events include “humping” of the individual cars to build the train in the yard; in humping, a car is pushed over a hump in the track in the yard, released and allowed to roll down the incline of the hump toward an awaiting car.

Train action events and yard impact events both subject the couplers of the cars to buff impacts, and train action events also subject the couplers of the cars to draft impacts. These impacts are transmitted from the couplers to the draft gear assemblies to the rail car body. That is, as the couplers are pulled or pushed, the movement is translated to the freight car body through the draft gear assemblies. Typical draft gear assemblies include a yoke element that is connected to the coupler through a pin or key, a coupler follower and a draft gear, as well as other elements. Generally, the coupler follower is positioned against or closely spaced from the butt end of the coupler in the draft gear pocket, within the yoke. The draft gear is positioned between the coupler follower and the rear stops of the draft sill.

In buff events, the butt end of the coupler moves inward against the coupler follower toward the rear stops of the draft sill. As the coupler and coupler follower are moved rearward, the shock of the movement is transferred to the draft gear. The draft gear typically absorbs and dissipates some of the energy from this shock through friction.

In draft events, slack is taken up between adjacent cars beginning at one end of the train and ending at the other end of the train. As a result of the slack being progressively taken up, the speed differences between the railcars increases as the slack at each coupler pair is taken up, with a resultant increase in buff and draft impacts on the couplers. This slack is taken up progressively, coupler pair by coupler pair.

There is an on going review of the weight of freight car and locomotive components in an effort to maintain strength and performance, while lessening the weight of such components. One known yoke for use in a locomotive draft gear assembly is made of Grade B cast steel and weighs about 500 pounds. The yoke of the present invention is usually made of Grade E cast steel and weighs about 288 pounds in a preferred embodiment. The weight reduction of about 42% is significant.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide our improved, lighter weight yoke for use in a locomotive draft gear assembly.

In one aspect, the present invention provides a yoke having a front wall, a back wall, a top strap and a bottom strap extending from the back wall toward the front wall. The top strap and bottom strap of the yoke are tapered to a reduced width at the back wall. The top strap and bottom strap also have a reduced thickness by an indentation of the outer surface of each along most of their length.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings,

FIG. 1 is a lower perspective view of a yoke in accordance with an embodiment of the present invention;

FIG. 2 is a top view of a yoke in accordance with an embodiment of the present invention;

FIG. 3 is a side view of a yoke in accordance with an embodiment of the present invention;

FIG. 4 is a top view of a draft gear assembly and coupler with a yoke in accordance with an embodiment of the present invention, and

FIG. 5 is a side view of a draft gear assembly and coupler with a yoke in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIGS. 1, 2 and 3 of the drawings, a yoke for use in a locomotive draft gear assembly is shown generally at 10. Such yoke is typically a unitary cast steel structure. Grade E steel is preferred. Yoke 10 is seen to comprise an elongated top strap 12 and an elongated bottom strap 14. Back wall 16 of yoke 10 and front wall 18 of yoke 10 are joined by top strap 12 and bottom strap 14.

Back wall 16 is shown as having an inner concave surface 17 adapted to abut against the complementary convex surface of a rear follower.

Front wall 18 is seen to comprise two side sections 28 that are spaced laterally and extend from top strap 12 to bottom strap 14. Front wall 18 is further seen to comprise a top section 22, center section 26, and bottom section 24. Each of front wall top section 22, front wall center section 26 and front wall bottom section 24 are seen to have a convex edge extending from a center forward most portion back into contact with front wall side sections 28. A draft pin retainer 20 is seen to extend downwardly from front wall bottom section 24. By such a design of front wall top section 22, front wall center section 26 and front wall bottom section 24, significant weight savings are provided with requisite strength.

Bottom strap 14 is seen to include indented section 32 of reduced thickness in a center area of the outer surface of bottom strap 14. The outer surface of top strap 12 contains a similar indented area 34 of lessened thickness in an effort to reduce overall weight of yoke 10. The area of reduced thickness in bottom strap 14 extends from a location inward from back wall 16 to a location inward of the intersection of bottom strap 14 with front wall side sections 28. The area of reduced thickness in top strap 14 extends from a location inward from back wall 16 to a location inward of the intersection of top strap 12 with front wall side sections 28.

Bottom strap 14 is also seen to have reduced lateral extent wherein the width of bottom strap 14 is lessened from front wall 18 intersection with side wall 28 toward back wall 16. A similar reduced lateral extent is present on top strap 12 whereby top strap 12 is reduced in width from front wall 18 intersection with side wall 28 toward back wall 16. The width sections of top strap 12 and bottom strap 14 decreases from about 14.4 inches at the intersection with side wall 28 to about 8.25 inches at back wall 16. Further, back wall 16 has a reduced width of about 5.5 inches. The reduced width of top strap 12 and bottom strap 14 and back wall 16 combine to provide further weight savings in the improved design of yoke 10.

Referring now to FIGS. 4 and 5, yoke 10 is shown as part of a draft gear assembly 50 wherein a coupler 63 is received within yoke front wall 18 utilizing pivot pin 65. Coupler 63 is comprised of pivot or butt end 66, shank 64 and coupler head 68. Knuckle 70 is seen to pivot within coupler head 68. Pivot pin 65 is seen to extend through openings in front wall top section 22, center section 26, and bottom section 24. An appropriate bar device extends through openings in pivot pin retainer 20 to keep pivot pin 65 retained in the coupler draft gear assembly.

Coupler follower 52 is usually a cast steel, generally rectangular structure. Coupler follower 52 is seen to be inserted between top strap 12 and bottom strap 14 of yoke 10 and adjacent the inner surface 19 of front wall 18. Rear follower 54 is quite similar to front follower 52 but is of a bit larger depth. Rear follower 54 is seen to have a rear face that is positioned adjacent inner surface 17 of back wall 16. Rear follower 54 is also positioned between top strap 12 and bottom strap 14. Both coupler follower 52 and rear follower 54 are usually comprised of cast steel.

Draft gear 56 is seen to be positioned between top strap 12 and bottom strap 14 of yoke 10, and is also positioned between rear wall 72 of coupler follower 52 and rear wall 74 of rear follower 54. Draft gear 56 is seen to comprise a series of plates 58, which are usually circular in cross section and metallic, usually of steel composition. Between each plate 58, elastomer pad 60 is located. As seen from FIGS. 4 and 5, a series of elastomer pads 60 and plates 58 comprise draft gear 56.

In a buff situation, when lateral force is applied through coupler shank 64 and pivot end 66 laterally into draft gear assembly 50, sufficient tolerance is provided in the opening for pivot pin 65 such that coupler butt end 66 contacts the front face of coupler follower 52 and imparts a laterally compressive force against draft gear 56. Draft gear 56 accordingly acts as a cushioning device to absorb some of the buff load from the coupler. In draft, when horizontal force is applied through coupler shank 64, such force is applied through pivot pin 65 into front wall 18 of yoke 10. 

What is claimed is:
 1. A yoke for use in a railway locomotive draft gear assembly, the yoke comprising: a front wall, a back wall, a top strap extending from the front wall to the back wall, a bottom strap extending from the front wall to the back wall, the front wall comprising two side sections, each side section extending vertically between the top strap and the bottom strap, the front wall further comprising a bottom support section, a center support section and a top support section, each of the bottom, center and the top support sections having a convex edge and extending laterally between the two side sections, and wherein the center support section has a thickness greater than the thickness of the bottom support section or the top support section, the top strap extending from the front wall to the back wall, the top strap having an outer surface that is indented inwardly from an intersection of the top strap with the front wall and from a second intersection of the top strap with the back wall, such inward indentation resulting in the top strap having a uniform reduced thickness along its length from a first location inward from the intersection of the top strap with the front wall and to a second location inward from the intersection of the top strap with the back wall, the top strap having an inner surface that is not indented from the intersection of the top strap with the front wall to the intersection of the top strap with the back wall, the bottom strap extending from the front wall to the back wall, the bottom strap having an outer surface that is indented inwardly from an intersection of the bottom strap with the front wall and from a second intersection of the bottom strap with the back wall, such inward indentation resulting in the bottom strap having a uniform reduced thickness along its length from a first location inward from the intersection of the bottom strap with the front wall and to a second location inward from the intersection of the bottom strap with the back wall, the bottom strap having an inner surface that is not indented from the intersection of the bottom strap with the front wall to the intersection of the bottom strap with the back wall, the back wall having at least one indented section on an inner surface extending from near the top strap to near the bottom strap.
 2. The yoke of claim 1 wherein the top strap having a first lateral extent at the intersection of the top strap with the front wall, the top strap lateral extent tapering to a lesser lateral extent at the intersection of the top strap with the back wall.
 3. The yoke of claim 2, wherein the lateral extent of the top strap at the intersection of the top strap with the back wall is about 67 per cent of the lateral extent of the top strap at the intersection of the top strap with the front wall.
 4. The yoke of claim 1 wherein the bottom strap having a first lateral extent at the intersection of the bottom strap with the front wall, the bottom strap lateral extent tapering to a lesser lateral extent at the intersection of the bottom strap with the back wall.
 5. The yoke of claim 4, wherein the lateral extent of the bottom strap at the intersection of the bottom strap with the back wall is about 67 per cent of the lateral extent of the bottom strap at the intersection of the bottom strap with the front wall.
 6. The yoke of claim 1, wherein the lateral extent of the top strap adjacent the front wall is about 14.4 inches, and the lateral extent of the top strap adjacent the back wall is about 8.25 inches, and wherein the lateral extent of the bottom strap adjacent the front wall is about 14.4 inches, and the lateral extent of the bottom strap adjacent the back wall is about 8.25 inches.
 7. A yoke for use in a railway locomotive draft gear assembly, the yoke comprising: a front wall, a back wall, a top strap extending from the front wall to the back wall, a bottom strap extending from the front wall to the back wall, the front wall comprising two side sections, each side section extending vertically between the top strap and the bottom strap, the front wall further comprising a bottom support section, a center support section and a top support section, each of the bottom, center and the top support sections having a convex edge and extending laterally between the two side sections, the top strap extending from the front wall to the back wall, the top strap having an outer surface that is indented inwardly from an intersection of the top strap with the front wall and from a second intersection of the top strap with the back wall, such inward indentation resulting in the top strap having a uniform reduced thickness along its length from a first location inward from the intersection of the top strap with the front wall and to a second location inward from the intersection of the top strap with the back wall, the top strap having an inner surface that is not indented from the intersection of the top strap with the front wall to the intersection of the top strap with the back wall, the bottom strap extending from the front wall to the back wall, the bottom strap having an outer surface that is indented inwardly from an intersection of the bottom strap with the front wall and from a second intersection of the bottom strap with the back wall, such inward indentation resulting in the bottom strap having a uniform reduced thickness along its length from a first location inward from the intersection of the bottom strap with the front wall and to a second location inward from the intersection of the bottom strap with the back wall, the bottom strap having an inner surface that is not indented from the intersection of the bottom strap with the front wall to the intersection of the bottom strap with the back wall, the back wall having at least one indented section on an inner surface extending from near the top strap to near the bottom strap.
 8. The yoke of claim 7 wherein the top strap having a first lateral extent at the intersection of the top strap with the front wall, the top strap lateral extent tapering to a lesser lateral extent at the intersection of the top strap with the back wall.
 9. The yoke of claim 7, wherein the lateral extent of the top strap at the intersection of the top strap with the back wall is about 67 per cent of the lateral extent of the top strap at the intersection of the top strap with the front wall.
 10. The yoke of claim 7 wherein the bottom strap having a first lateral extent at the intersection of the bottom strap with the front wall, the bottom strap lateral extent tapering to a lesser lateral extent at the intersection of the bottom strap with the back wall.
 11. The yoke of claim 10, wherein the lateral extent of the bottom strap at the intersection of the bottom strap with the back wall is about 67 per cent of the lateral extent of the bottom strap at the intersection of the bottom strap with the front wall.
 12. The yoke of claim 7, wherein the lateral extent of the top strap adjacent the front wall is about 8.25 inches, and the lateral extent of the top strap adjacent the back wall is about 5.5 inches, and wherein the lateral extent of the bottom strap adjacent the front wall is about 8.25 inches, and the lateral extent of the bottom strap adjacent the back wall is about 5.5 inches. 